douyin-downloader adds desktop client for multi-platform downloads

As short-form video platforms tighten scraping constraints, douyin-downloader stands out by using a dual-engine architecture that bridges high-performance API requests with automated browser rendering. Seamless transitions to Playwright headless automation maintain resilience when API pagination hits verification challenges, while SQLite storage ensures deduplication, incremental updates, and resume capabilities across large creator catalogs. Expanding beyond CLI scripts into a multi-platform desktop client broadens its utility for archiving TikTok and YouTube content alongside Douyin. Additionally, FastAPI serving and automated transcription hooks make the tool easily adaptable for automated media processing pipelines.